Mm.. depends what you need at the moment..  u needa branch out between PVP , Castle Rush and Dragon Raid. For me at the moment if for pvp i would want a Heavenia.. so far theres no heroes that has passive immune against stun debuff for the team, stun debuff and passive invincible for 2 turns make her a wanted char in PVP. if Dragon Raid and PVP purpose Velika is good, reducing magic damage for team, and her AOE is quite pain if well equip and +5. Velika is not the most preferable if compared to Espada and Shean but still a good option if dont have both yet, since Dragon Raid requires 2 teams (10 heroes)

reddit people say is to fix the friendship bug option

This is my noob strat,

1) 1-4 formation, daily 7K at the back (depend on which 7K)
2) front Yuri, Ruri/Ariel, Victoria, Jupy, dont care wat lvl all i needed is the buff for first strike.
3) +physical att for leader, mastery put 10% counter other all attack
4) first buff Victoria, then 7K aoe
5) if 7K able to clear first round without losing HP, it should be able to solo 2nd round for 60th++ floor
6) retry a few times if is close, some lucky critical strike might just do the job

Hope it help 

Yeah same here...4* is the highest I could get from rare tix pull.... is it better to use single rare tix pull?